Re: [kvm-devel] Guest kernel hangs in smp kvm for older kernels priorto tsc sync cleanup

[Avi Kivity]

Ingo Molnar wrote:
> * Avi Kivity <avi@xxxxxxxxxxxx> wrote:
>
>   
> > Avi Kivity wrote:
> >     
> > >  Testing shows wrmsr and rdtsc function normally.
> > >
> > > I'll try pinning the vcpus to cpus and see if that helps.
> > >
> > >       
> > It does.
> >     
>
> do we let the guest read the physical CPU's TSC? That would be trouble.
>
>   

vmx (and svm) allow us to add an offset to the physical tsc.  We set it
on startup to -tsc (so that an rdtsc on boot would return 0), and
massage it on vcpu migration so that guest rdtsc is monotonic.

The net effect is that tsc on a vcpu can experience large forward jumps
and changes in rate, but no negative jumps.

--
error compiling committee.c: too many arguments to function
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